Respirator mask



Aug. 5, 1958 J. D. HILL RESPIRATOR MASK Filed May 3, 1954 INVENTOR. JOHN 0 HM ATTORNEY United States Patent O RESPIRATOR MASK John D. Hill, Cleveland, Ohio, assignor to Flexo Products, Inc., Cleveland, Ohio, a corporation of Ohio Application May 3, 1954, Serial No. 427,106 12 Claims. (Cl. 128-146) This invention relates to respirators, more particularly to mask type respirators such as described and claimed in my prior United States Patents No. 2,578,007 issued December 11, 1951 and Des. 161,337 issued December 26, 1950.

From time to time it becomes necessary to replace or cleanse a'respirator filter element when it is soiled or loaded with dust or other foreign particles. The old filter may be cleansed as by washing and replaced between the clamping members for re-use, or it may be discarded and replaced by a new one.

The general object'of the invention is to provide a mask type respirator of simplified construction and few parts, a respirator which can be instantly disassembled, removed or replaced by hand, a respirator which facilitates removal and replacement of the filter element. As a preferential arrangement the outer of the separable frame members which clamps the filter element in place against the inner of the frame members is secured to the latter by means independent of the head band or other attaching means so that the frame can be separated while the inner member remains in place on the face of the wearer.

In respirators of the character referred to a filter element is disposed across a breathing opening defined by aligned apertures in separable mask parts, the filter element being marginally clamped between such parts. So that the respirator parts will retain a secure grip on the margins of the filter element, the present invention, as one of its more specific objectives, contemplates the provision of specialized filter holding formations or teeth on the confronting portions of such respirator parts. More specifically it is contemplated to provide a number of teeth or protuberances on one of the respirator parts so positioned as to bite into or become embedded in the margin of the filter element. In the best version, presently known, a series of spaced protuberances or teeth are formed on the confronting surfaces of each of the respirator parts, the teeth of one series preferably being in alternating relation with respect to the teeth of an- .other series.

These filter holding teeth are arranged in rows extending in lines substantially paralleling the margins of the frame members of the respirator that define the breathing opening. The row or rows of teeth on one of the frame members are closer to the breathing opening than are the row or rows of teeth on the other or confronting frame member so that the teeth of one frame member engage the filter element relatively close to the breathing opening, the teeth on the other of the frame members engaging the filter element at a gerater distance from the breathing opening.

Another objective of the invention is to provide: a multiple part respirator mask of the character mentioned in which the parts are cooperatively shaped to locate one relative to the other in assembly and to resist relative lateral shifting in use while clamping and holding a filter element between them. This objective is largely achieved by forming the outer part, intowhich is received or nested the inner part, with a nasal portion deeper than its labial portions so asto provide a;locating .and retaining socket for the nasal portion of the innerrespirator part. Y A

A still further refinement having to do with the locating and holding together of the separable parts is the extension of the inner part side portions rearwardlybeyond the ends of the outer part side portions. The outer respirator part side portions thus do not completely cover the side portions of the inner part. By this arrangement the inner respirator part is providedwith rearwardly extending tabs unobstructed by the outer part and to which the ends of an attaching head band-maybe secured. Forwardly of the points of attachment of the head band the side tabs of the inner respirator part are formed with hornlike projections over which are received the side portions of the outer respirator part. Such horns are curved rearwardly in the provision of interlocks with the frame member received over the horns so that the frame members are secured firmly together in predetermined relative positions. When the frame members of the mask or one of them are molded of resilient, deformable plastic material such as polyethylene the horn means is desirably shaped in the molding operation as an integral part of the particular frame member having the horn means. The resilient deformable nature of the plastic permits deformation of the horns in assembly and permits a strong interlock to be established and maintained which prevents inadvertent separation ofthe respirator parts in normal use.

So that the filter element can be removed for cleansing and easily replaced, or another filter element substituted, provision is made for removing the outer frame member from the inner without disturbing the position of the inner frame member on the face of the wearer, this being one of the objectives of the invention. Such objective is attained by making the inner frame member with sides having tab portions extended rearwardly beyond the rearmost edge of the outer'frame member. These rearwardly extending portions of the inner frame member, while being integral with the clamping portions that hold the filter element in place and while snugly embracing the cheeks of the wearer to locate and hold the respirator in the desired position of use, constitute attachment tabs to which are secured the ends of a headband of rubber or other elastic material. In the arrangement'described the horn means used to interlock one frame to the other is disposed rearwardly of the corners of the breathing opening and the headband is attached to the rearwardly extending tab portions of the inner frame member at points spaced rearwardly of the horns. Each horn is thus located intermediate the edge of the breathing opening and one of the points of attachment of the headband.

Another object is to provide a mask type respirator of separable inner and outer members in which the outer member has a relativelydeep concave nasal bridge portion for receiving a mating portion of the inner member to-locate and retain the latter.

Still further objects and advantages relate to certain details of construction and combinations and arrangements of parts which are apparent in the following description of a preferred embodiment of the invention which represents the best mode of carrying it out. This description is made is connection with the accompanying drawings forming a part of this specification. Like parts throughout the several views of the drawings are indicated by the same letters and numerals of reference.

In the drawings: I

Fig. l is a collective view showing the respirator of the present invention in expanded perspective;

Fig. 2 is an elevation of the filter element reduced in scale relative to Fig. 1;

Fig. 3 is a front'elevation of the assembled respirator, the headband being omitted and part of the outer frame member and of the filter being broken away to show the interlock between the filter element and one of the horns that holds the outer member in place;

Fig. 4 is a vertical section through the center of the respirator taken substantially along the line 4-4 of Fig. 3, the headband being removed and parts being broken aw y n m v d;

Fig, 5 is a fragmentary sectional detail taken substantially alongthe line 55 of Fig. 3 and enlarged; and

Fig. 6 is enlarged fragmentary sectional detail taken as though along the line 66 of Fig. 3, the attachment of one end of the rubber headband to the inner frame member being illustrated.

The respirator of the present invention is like that of the. patent referred to and comprises inner and outer frame members A and B, respectively, and an attaching headband C. The frame members are formed of shape-re taining material, preferably being relatively thin and somewhat resilient so as to conform to varying facial contours of different persons. Although the frame members may be stampings of thin metal, such as aluminum sheet, it is preferred to use a soft plastic like or such as polyethylene, although satisfactory results are obtained with thermosetting or thermoplastic materials. The frame members can be formed as by injection molding of a suitable plastic material, or, if athermoplastic is used, the frames may be formed of sheet material cut and shaped in presses.

' The inner frame member is cupped to receive the nose and mouth of the wearer and has a horizontal bottom portion 1 which extends across and rests against the chin of the wearer. Side or check portions 2 and 3 are oblique to the chin portion and are curved rearwardly away from the plane of the chin or bottom portion 1, the oblique side portions having inwardly directed confronting faces which are normally disposed flatwise against the checks of the wearer.

In the front of the mask of the inner frame A is formed with an inverted heart or V shaped breathing opening 5 across which is disposed filter element D which may be formed of foam latex, fibrous glass, cotton gauze, or a mat or pad of a synthetic fiber or a suitable combination of fibers. The inner frame member A includes a front portion 6 disposed across the top of the breathing opening and located approximately in the same plane as the chin portion 1. The front portion is integrally joined to a rearwardly extending angularly disposed flange 7 which extends along the top edges of the side portions 2 and 3, providing an enclosing bridge for the wearers nose.

To obtain an effective seal between the respirator edges and the face of the wearer, the rear edges of the oblique sides 2 and 3 are formed with outwardly curving integral tab portions 4 that fit in the angles between the wearers nose and cheeks. These tabs are generally thinner than the sides and other parts of the frame member A, thus being more flexible to obtain the desired yielding and conforming comfortable fit. Desirably, and as shown, the tabs taper toward their free edges so that the latter have extreme flexibility.

The outer frame member B is complementally shaped with respect to the inner frame member but is of less area or extent than the latter. Breathing opening 8 in theouter frame member B corresponds in shape to the breathing opening 5 of the inner frame member.

The filter element D may be any suitable porous material in. the form of a woven gauze or felted mat of fibrous glass, natural or synthetic fiber, or it may be terrycloth, natural or artificial sponge or foam latex.

The outer frame member includeschin, oblique side and top front portions 11, 12, 13 and 16 corresponding respectively to the portions 1, 2, 3 and 6 of the inner frame member A. These corresponding portions of the inner and outer frame members are complementally shaped and have confronting faces which clamp between them marginal portions 14 of the filter element D around the entire periphery of the latter.

Along the upper edge of the top front portion 16 of the outer frame member is formed an integral angularly disposed and rearwardly extending flange 17 which is arranged to overlie a relatively large portion, about half, of the nasal bridge or arch 7 of the inner frame memher to locate and hold the two frame members in predetermined relative positions and to support the outer frame member on the inner. Piloting or guiding of the frame members to locate them in predetermined relation with respect to one another is provided by the lateral flange 17 which has sliding engagement on the upper surface of the nasal bridge 7 as the frame members are moved together in assembling the respirator.

The rearward extent of the outer member bridge portion 17 over the inner member bridge portion 7 is both relatively and actually much greater than the extent of the outer member oblique side portions 12 and 13 over the corresponding portions of the inner member A. Thus the front portion 16 and the nasal bridge portion 17 of the outer member B cooperatively define a relatively large pocket 15 that locatingly receives the complemental part of the inner member comprising the front and nasal bridge portions 6 and 7 respectively.

At each side of the mask respirator the side portions 12 and 13 of the outer frame member are formed adjacent their rearmost ends with vertically elongated openings 13 which receive laterally projecting extensions or horns 19 formed integrally on the adjacent side portions 2 and 3 of the inner frame member A. Each of the horns or extensions 19 is curved rearwardly and received in the associated socketlike aperture 18 of the outer frame member B with a snap fit. Thus the horn extensions and the socket formations in which received constitute interlocking means for retaining the frame members in assembled relation. The rearmost side edges of the generally triangular filter element D are notched out as indicated at 23 in the provision of locating recesses that receive the horns 19.

The headband C is in the form of an adjustable length flexible strap or tape preferably comprising elastic strip rubber to retain the respirator frame snugly against the wearers face. The band may be of molded rubber having integral embossed formations at spaced intervals on its inside surface. Suitable elasticity is also present in conventional elastic tape made of woven fabric material incorporating elastic or rubber strands. In assembling the respirator the ends of a suitable length of band or tape are threaded through openings 20 in rearwardly extending integral tabs 24 of the inner part side portions 2 and 3. The ends of the tape or band after passing through the openings 20, may be reversely bent and secured to slide buckles on the body of the band or, as shown, the rubber band ends may have integral enlargements or knobs 22 which are shaped and sized to permit insertion through the slots 20 in assembled but resist withdrawal in normal use. A fastener comprising separable buckle parts 26 and 27 joins the ends of the two rubber strips comprising the headband, the buckle parts permit adjustment in effective length of the headband.

The tabs 24 which constitute anchorages for the head band ends are to the rear of the rearmost portions of the outer frame member B and the anchorage slots 20 are thus clear and to the rear of the fastening horns 19 whereby interference between the headband and the outer frame member is avoided.

Augmentation of the grip of the frame members on the filter element D is obtained by integral square shaped teeth extending in rows along the cheek and chin portions of *the members. In the preferred arrangement and distribution illustrated a series of teeth 31 are arranged in a row paralleling and relatively close to the edge of the breathing opening '5 of the inner member. Similar seriesof teeth 32 are arranged along the oblique side portions 2 and 3 of the inner member parallel to and relatively close to the breathing opening. The teeth 31 and 32 project toward the confronting internal surfaces of the corresponding chin and side portions of the outer frame part B and the latter is preferably formed with'teeth 33 on the chin portion 11 and teeth 34 on the oblique side portions 12 and 13. The rows of teeth 33 and 34 are at different spacings from the breathing opening than are the corresponding tooth rows of the inner member, the latter being closer to such opening so that the rows of teeth act in pairs, one row on each frame member, to bend or form waves in thefilter element parallel to its edges. As a refinement of the invention to facilitate assembly and filter replacement the rows of teeth are each of less length than the corresponding sides of the breathing opening, the tooth rows being discontinuous across the junctures between the chin portions of the frame pans and the adjacent oblique side portions and across the junctions at the nasal bridges between the two side portions. An integral endless bead 35 is formed on the outer member B andextends unbroken about the entire breathing opening. This bead projects into the plane of the opening and is. engaged against the outward surface of the filter element.

' 'The inner and outer frame members A and B readily may be separated from one another for renewal, and replacement of the filter D while the inner frame member remains in place on the wearer. To change or replace the filter element D while the respirator is being worn, the user draws outwardly on one or both of the side portions 12and 13 of the outer frame member to'release the snap fit interlock of the horn extensions 19in the apertures 18. The outer frame member B is thus released from the inner frame member A, allowing the latter to remain in position over the nose and mouth. With the frame members thus separated the filter element D is released from clamped position between the confrontingfaces of the frame members, permittingit tobe removed or withdrawn from the breathing opening in the front of the mask. With the outer frame member stillwithdrawn a new or replacement filter is then disposed'across the breathfmg opening of the inner frame member and the outer frame member returned .to clampingposition The side portions 12 and 13 are received 'oventhe holdinghorns 19 with the latter-locatingly received in the notches 23 of the filter element D.

:' Should the respirator be first removed by the wearer for replacementrorrenewal of the filter element, the frames .may be; separated by springing apart the side portions 12 and 13 of the outerframe member to withdraw them from off the extensions or horns 19,'thus releasing the frame members from their clamping engagement on the filter element.

In, addition to providing an interlocking connection between the frame members, the horn formations 19, in cooperation with the locating nasal bridge flange 17, serve as locating indexes which correctly aline the frame members A and B relative to one anotherand to the filter D'so as to position-the breathing openingS of the inner frame member in precise relation to the breathingopening 8 of the outer frame member. This correct positioning of the parts is effective to maintain the proper relationship between the filter locking teeth formed on the frame members about the'breathing opening.

In accordance with the provisions of the patent stat- Utes, the principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changesjn construction being resorted to as desired, it

6 being .understood that the embodimentshown ,in' the drawing and illustrated above is given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What I claim and desire to secure by.Letters Patent of the United States is:

1. A mask type respirator comprising separable shape retaining inner and outer frame members, a filter element receivable between the frame members, the frame members having oomplementally formed portions extending around a breathing opening for clamping the edges of the filter element therebetween'and supporting the element across the breathing opening, the confronting surfaces of said clamping portions of .the frame members being formed with projecting teeth, the teeth 'on one of the members being closer to the breathing opening than are the teeth on the other of the members, and means holding the frame members together in said clamping relation.

2. A mask type respirator comprising separable shape retaining inner and outer frame members, a filter element receivable between the frame members, the frame members having complementally formed portions extending around a breathing opening for clamping the edges of the filter element therebetween and supporting the element across the breathing opening, the inner frame member having teeth projecting toward the outer member, the outer member having teeth projecting toward the inner member, the inner member teeth being closer to the breathing opening than the outer member teeth, and means holding the frame members together in said clamping relation. I

3. A mask type respirator comprising inner and outer frame members, each member having a nasal bridge portion at the top, a horizontal chin portion at the bottom and oblique cheek portions connecting the bridge and chin portions to define a breathing opening, integral teeth extending in rows along the cheek and chin portions of the members, each row of teeth on one ofthe members being at a different spacing from the breathing opening than the corresponding row of teeth on the other of the members, and a filter element disposed across the breathing opening and clamped between the teeth of the members.

4. A mask type respirator comprising inner and outer frame members, each member having a nasal bridge portion at the top, a horizontal chin portion at the bottom and oblique cheek portions connecting the bridge and chin portions to define a breathing opening, the.

bridge portion of the outer member being concave and deeper than the cheek portions thereof to provide a localized pocket to receive and locate the bridge portion of the inner member, integral teeth extending in rows along the cheek and chin portions of the members, each row of teeth on one of the members being at a different spacing from the breathing opening than the cone sponding row of teeth on the other of the members, and a filter element disposed across the breathing opening and clamped between the teeth of the members.

5. A mask type respirator comprising inner and outer frame members, each member having a nasal bridge portion at the top, a horizontal chin portion at the bottom and oblique cheek portions connecting the bridgeand chin portions to define a breathing opening, integral teeth extending in rows along the cheek and chin portions of the members, each row of teeth on one of the members being at a different spacing from the breathing opening than the corresponding row of teeth on the other of the members, the rows of teeth each being shorter than the breathing opening edge defined'by that portion of the frame member on which the tooth row is formed and being discontinuous across the junctures between the side portions at the nasal bridge and between each of the side.

7 portions and the chin portion, and a filter element disposedacross the breathing opening and clamped between theteeth of the members.

6.- A mask type respirator receivable over the nose and mouth of a wearer, said respirator comprising separable inner andouter frame membersof resilient deformable shape retaining material each having a breathing opening,tthe breathing opening in each member being defined by top and bottom edges which converge toward the sides of the opening, a filter element, the frame members being complementally formed to fit together as an assembly in predetermined nested relation with their openings in register and to clamp between them the margins of the filter element. in supporting the filter element across the registered breathing openings, the inner frame member having side portions which project rearwardly beyond the outer member and which are adapted to overlie the cheeks of the wearer, an elastic band for holding the frame members in place on the head of the wearer over the wearers nose and mouth, means attaching the headband to the rearwardly projecting portions of the inner frame member at points spaced rearwardly from the outer frame member, one of the frame members being formed with projecting horns located at points spaced rearwardly from the rearmost edges of the breathing opening in such one member and substantially on a line which connects the points of attachment of the headband to the assembled frame members and which line represents substantially the direction of the forces exerted and acting on the inner frame member by the elastic headband in holding the frame members in place, the other of the frame members being formed with sockets to receive the horns in the provision of interlocking connections holding theframe members together in assembled relation with the filter element clamped therebetween, said sockets being located at points spaced rearwardly from the rearmost edges of the breathing opening in such other member, the location of the horn interlocks on the lines of action of the headband forces serving effectively to transfer the headband strain from the inner frame member to the outer frame member at points on the sides of the respirator each spaced rearwardly from the registered breathing openings, the outer frame member being completely removable from the inner frame member upon separation of the interlocking horn connections to release the filter element for removal and replacement of the latter while the attached headband holds the inner member in place on the wearers head.

7. A mask type respirator receivable over the nose and mouth of a wearer, said respirator comprising separable inner and outer frame members of resilient deformable shape retaining material each having a breathing opening, the breathing opening in each member being defined by top and bottom edges which converge toward the sides of the opening, a filter element, the frame members being complementally formed to fit together as an assembly in predetermined nested relation with the inner member within the outer member, with their openings in register and to clamp between them the margins of the filter element in supporting the filter element across the registered breathing openings, the inner frame member having side portions which project rearwardly beyond the outer member and which are adapted to overlie the checks of the wearer, an elastic band for holding the frame members in place on the head of the wearer over the wearers nose and mouth, means attaching the headband to the rearwardly projecting portions of the inner frame member at points spaced rearwardly from the outer frame member, one of the frame members being formed with projecting horns located at points spaced rearwardly from the rearmost edges of the breathing opening in such one member and substantially on a line which connects the points of attachment of the headband to the assembled frame members and which line represents substantially the direction of the forces exerted and acting on the inner frame member by the elastic headband in holding the frame members in place, the other of the frame members being formed with through apertures to receive and through which project the horns, said horns being curved rearwardly in the provision of interlockingconnections holding the frame members together in assembled relation with the filter element clamped th'erebetween, said apertures being located at points spaced rearwardly from the rearmost edges of the breathing opening in such other member, the location of the horn interlocks on the lines of action of the headband forces serving effectively to transfer the headband strain from the inner frame member to the outer frame member at points on the sides of the respirator each spaced rearwardly from the registered breathing, openings, the outer frame member being completely removable from the inner frame member upon separation of the interlocking horn connections to release the filter element for removal and replacement of the latter while the attached head band holds the inner member in place on the wearers head, and in the assembled respirator the horns project: ing from the through apertures in the other frame member and being detectable by feel in determining that the interlocking connections are completed. 7

8. A mask type respirator receivable over the nos and mouth of a wearer, said respirator comprising separable inner and outer frame members of resilient deformable shape retaining material each having a breathing opening, the breathing opening in each member being defined by top and bottom edges which converge toward the sides of the opening, a filter element, the frame members being complementally formed to fit together as an assembly in predetermined nested relation with the inner member within the outer member, with their openings in register and to clamp between them the margins of the filter element in supporting the filter element across the registered breathing openings, the inner frame member having side portions which project rearwardly beyond the outer member and which are adapted to overlie the cheeks of the wearer, an elastic band for holding the frame members in place on the head of the wearer over the wearers nose and mouth, means attaching the headband to the rearwardly projecting portions of the inner frame member at points spaced rearwardly from the outer frame member, the inner frame member being formed with outwardly projecting horns located at points spaced rearwardly from the rearmost edges of the breathing opening in the inner member and substantially on a line which connects the points of attachment of the headband to such inner frame member and which line represents substantially the direction of the forces exerted and acting on the inner frame member by the elastic headband in holding the frame members in place, the outer frame member being formed with sockets to receive the projecting horns in the provision of interlocking connections holding the frame member together in assembled relation with the filter element clamped therehetween, said sockets being located at points spaced rearwardly from the rearmost edges of the breathing opening in the outer member, the location of the horn interlocks on the lines of action of the headband forces serving effectively to transfer the headband strain from the inner frame member to the outer frame member at points on the sides of the respirator each spaced rearwardly from the registered breathing openings, the outer frame memher being completely removable from the inner frame member upon separation of the interlocking horn connections to release the filter element for removal and replacement of the latter while the attached headband holds the inner member in place on the wearers head, and the-horns projecting from the inner member so held in place constituting locators facilitating reassembly of the outer member after replacement of the filter element. 9. A mask type respirator receivable over the nose and mouth of a wearer, said respirator comprising separable inner and outer frame members of resilient deformable shape retaining material each having a breathing opening, the breathing opening in each member being defined by top and bottom edges which converge toward the sides of the opening, a filter element of flexible sheet material-shaped similarly to the breathing openings in the frame members and slightly larger than such openings so as to be adapted to be marginally clamped between the frame members, the frame members being complementally formed to fit together as an assembly in predetermined nested relation with their openings in register and to clamp between them the margins of the filter element in supporting the filter element across the registered breathing openings, the inner frame member having side portions which project rearwardly beyond the outer memberand which are adapted to overlie the cheeks of the wearer, an elastic band for holding the frame members in place on the head of the wearer over the wearers nose and mouth, means attaching the headband to the rearwardly projecting portions of the inner frame member at points spaced rearwardly from the outer frame member, one ofthe frame members being formed with projecting horns located at points spaced rearwardly from the rearmost edges of the breathing opening in such one member, the filter element being formed in its marginal portions outside the area disposed across the breathing openings with recesses adapted to receive the projecting horns to locate the filter element in assembly in predetermined relation to the said one frame member and to provide an interlock between the filter element and such one frame member, the other of the frame members being formed with sockets to receive the horns in the provision of interlocking connections holding the frame members together. in assembled relation with the filter element clamped therebetween, said sockets being located at points spaced rearwardly from the rearmost edges of the breathing opening in such other member and the outer frame member being completely removable from the inner frame member upon separation of the interlocking horn connections to release the filter element for removal and replacement of the latter while the attached headband holds the inner member in place on the wearers head, the horn interlocks serving effectively to transfer the headband strain from the inner frame member to the outer frame member at points on the sides of the respirator each spaced rearwardly from the registered breathing openings.

10. A mask type respirator receivable over the nose and mouth of a wearer, said respirator comprising separable inner and outer frame members of resilient deformable shape retaining material each having a breathing opening, the breathing opening in each member being defined by top and bottom edges which converge toward the sides of the opening, a filter element of flexible sheet material shaped similarly to the breathing openings in the frame members and slightly larger than such openings so as to be adapted to be marginally clamped between the frame members, the frame members being complementally formed to fit together as an assembly in predetermined nested relation with their openings in register and to clamp between them the margins of the filter element in supporting the filter element across the registered breathing openings, the inner frame member having side portions which project rearwardly beyond the outer member and which are adapted to overlie the cheeks of the wearer, an elastic band for holding the frame members in place on the head of the wearer over the wearers nose and mouth, means attaching the headband to the rearwardly projecting portions of the inner frame member at points spaced rearwardly from the outer frame member, the nner frame member being formed with outwardly proectmg rearwardly inclined horns located at points spaced rearwardly from the rearmost edges of the breathing 10 opening in such inner member and substantiall'ywn a line whichconnects the points of attachment of the headband to the inner framem'emberrand -which line represents substantially the direction-of the forces-exerted and acting on the inner frame member by the elastic headband in holding the frame members in. place, the .filter element being formed in its 'marginalportions outside the area disposed across the breathingopenings with recesses which receive the horns to locate the filter element in assembly and to interlock the filter element and the inner frame member in predetermined-relation, the outer frame member being formed with through apertures to receive the projectinglhorns in thetprovision of interlocking connections holding'the frame members together in assembled relation with the located filter element clamped therebetween, said apertures being located at points spaced rearwardly from the rearmost edges of the breathing opening in such outer member, tth'ei loca tion of the horn interlocks on the lines of actionv of the headband forces serving effectively to transfer the headband strain from the inner frame member to the outer frame member at points on the sides of-the respirator.

each spaced rearwardly from the registered breathing openings, and-the outer frame member being completely removablefrom the inner frame member upon separation ,of the interlocking horn connections to release'the filter element for removal and replacement of the latter while ,the attached headband holds the inner member in, place on the wearers head, the horns projecting outwardly from'the inner member so held in place and'constituting locators adapted to be felt to facilitate reassembly of the outer member on the inner member, and in the assembled respirator the'horns projectingoutwardly from the through apertures in the outer member and being adapted .tobe detected by feel on the outside of the respirator in determining that the interlocking connections are com- .pleted. i i

11. A mask type respirator device receivable over the nose and mouth of a'wearer, said respirator comprising separableinner and outer shape retaining plastic frame members nested together and; each formed in one piece .with a breathing opening registered with the breathing opening of the other,'each frame member comprising a bottom chin element and oblique converging top elements, the oblique elements having upper ends connected together centrally of the device, said oblique elements having lower ends connected to opposite ends of the chin element, the inner member including a nasal portion comprising tapered elements joined and angularly disposed relative to one another in the provision of an arch to receive the nose of the wearer, one tapered element being angularly disposed relative to and joined to longitudinally extending edge of one of the oblique elements of the inner frame member, the other tapered element being similarly disposed and joined relative to the other of the oblique elements of such inner frame member, the outer member including a nasal portion of elements similarly disposed relative to one another and to the oblique elements of such outer member and similarly secured to one another and to such oblique elements, the nasal portions of the frame members each being of greatest width adjacent the center connections of the respective oblique elements and the nasal arch of the outer frame being substantially half the width of the nasal arch of the inner frame, the angular relation between the tapered nasal elements of the inner frame nasal portion and the angular relation between each tapered nasal element and the oblique element to which it 1s joined providing an internal concavity in the inner member at one end of the nose receiving arch and also providing a corresponding external convexity, the corresponding angular relations between the nasal and obl que elements of the outer frame member providing an nternal concavity complemental to the external convexity of the inner frame member and receivable over the latter, whereby the nasal portion of the outer frame is located over the nasal portion of the inner name member-in predetermined straddling relation and is eupportedthereon in use, a filter element clamped between the frame members and supported thereby across the registered breathing openings, the straddling relation and relative widths of the nasal arches permitting sliding'c'o'n'tact and guiding of the outer frame nasal portion on the inner frame nasal portion in clamping the filter element between the frame members in assembly, and a headband secured to-oneyo'f the frame members to hold the device in place on the head of the wearer.

12. A mask type respirator device receivable over the nose and mouth of a wearer, "said respirator comprising separable inner and outer shape retaining plastic ir'ar'ne members nested together and each formed in "one piece with a breathing openingregistered with the breathing opening of the other, eachframe member comprising a bottom chin element and oblique converging top elements the oblique elements having upper ends connected together centrally of the device, said oblique elements having lower ends connected to opposite ends of the chin element, the inner member including a nasal portion comprising tapered elements joined and angularly disposed relative to one another in the provision of an arch to receive the nose of the wearer, one tapered element being angularly disposed relative to and joined to longitudinally extending edge of one of the oblique ele 'ments of the-inner frame member, the other tapered element being similarly disposed and joined relative to the other of the oblique elements of such inner frame member, the outer member including a nasal portion of elements similarly disposed relative to one another and to the oblique elements of such outer member and similarly secured to one another and to such oblique elements, the nasal portions of the frame members each being of greatest width adjacent the center connections of the respective oblique elements and the nasal arch of the outer frame being substantially half the width of the nasal arch of the inner frame, the nasal elements of the outer frame member each being narrower than the corresponding element of the inner frame member and having a line of connection with the oblique element 12 shorter than the line of connection bet-ween the corresponding tapered nasal and oblique elements of the inner frame member so "that in use the nasal arch of the inner frame projects beyond the overlying elements of the outer frame na'sal arch, each of the tapered elements of the inner frame nasal arch being' formed with an outwardly curved flange thinner and of greater flexibility than the other parts "of the nasal arch, said curved flanges being located along and shorter than the rear edges of the tapered nasal elements *for engagement with the face ot the wearer in'the regions of the depressions between the nose and "cheeks, the angular relation between the tapered nasal elements ofthe inner frame nasal portion and the angular relation between each tapered nasal element and the oblique element to which it is joined providing an internal concavity in 'the inner member at one end of the nose receiving arch and also providing a corresponding external convexity,

the corresponding angular relations between the nasal and oblique elements of the outer frame member providing an internal concavity complementa'l to the external convexity of the inner frame member and receivable over the latter, whereby the nasal portion of the outer frame member is located over the nasal portion of the inner :frame "member in predetermined straddling relation and is supported thereon in use, a filter element clamped between the frame members and supported thereby across the registered breathing openings, the

straddling relation'and relative widths'of'the-nas'al arches permittingsliding Contact and guiding-of-the outer frame nasal portion on the innerframe nasal'porti'on in clamping the filter element between the frame members in assembly,and a headband secured to one of the fr'arn'e members to hold the device in place'on the head of the wearer.

References Cited in the file of this patent UNITED STATES PATENTS 2,578,007 fHiIl Dec. 11, I951 FOREIGN PATENTS L142 Great Britain Jan; 16, 1904 of 1903 

